Sodium super ionic conductor (NASICON) and related sodium zirconium phosphate NaZr2P3O12 (NZP) and niobium titanium phosphate NbTiP3O12 are well studied [1-6] due to their important properties of (i) low thermal expansion behavior [5-9], (ii) fast ionic conductivity [2] and (iii) high temperature stability [2]. They are used as heat exchangers and I mirror blanks for space technology, catalyst supports, high temperature fuel cells, possible host for radioactive waste and as humidity and gas sensors [10-15]. Their general formula is AMM′P3O12 where, ‘A’ can be alkali, alkaline earth or Cu2+ ion, M and M′ can be tri-, tetra- or pentavalent transition metal ion. The structure is characterized by corner sharing of PO4 tetrahedra with MO6, (and M′O6,) octahedrai [16,17]. The three dimensionally linked interstitial space can accommodate ions as H+ or as large as Cs+ This space can also remain vacant as in NbTiP3O12 [18]. The structure is flexible for substitution at A, M or M′ sites, giving rise to a large number of closely related compounds. Among the NASICONs, copper NASICONs are relatively less investigated [19-22]. In this paper, we report the preparation, characterization, electron spin resonance (ESR) and photo acoustic (PA) studies of Cu0.5—NbAlP3O12 (CNP) and HNbAlP3O12 (HNP).